Semiconductor devices, in particular field-effect controlled switching devices such as a Metal Oxide Semiconductor Field Effect Transistor (MOSFET) and an Insulated Gate Bipolar Transistor (IGBT) have been used for various applications including but not limited to use as switches in power supplies and power converters, electric cars, air-conditioners, and even stereo systems.
Particularly with regard to power applications, vertical semiconductor devices with two power metallization arranged on opposite sides of a semiconductor substrate and a control metallization arranged on one of the sides are often used. For example, a vertical MOSFET may have a source metallization and a gate metallization on the front side of the semiconductor substrate, and a drain metallization on the back side of the semiconductor substrate. To ensure reverse blocking voltage in an off-state, ring-shaped field-plates on drain potential surrounding an active device area with a plurality of MOSFET-cells each having a gate electrode may be used at or close to the front side. The ring-shaped field-plates may be contacted to the drain metallization via a metal contact arranged on the front side in a corner region of the semiconductor substrate. Due to design requirements of the metallizations, a distance between gate fingers or gate runners of the gate metallizations and the gate electrodes may be larger for gate electrodes closer to the corner region. This may result in a higher gate resistance of gate electrodes closer to the corner region.
For these and other reasons there is a need for the present invention.